Database systems are collections of files stored on computers or other linked systems such as the Internet. The files together contain all the information about a topic or related topics. Generally, a file system is used to “file away” information which a user will later retrieve for processing. A file typically resides in directly accessible storage and can be manipulated as a unit by file system operations. The file system allows a user the means for storing data in files, the means for accessing the data in those files, the means for managing direct access to storage space where the files are stored, and the means for guaranteeing the integrity of those files.
Database systems are used by organizations to manage information about clients, orders, client accounts, and so forth. In addition, organizational databases are maintained that manage information about organization structure, employees, position, job, accounts, etc. When dealing with clients and orders, the organization often needs to locate and contact the appropriate employee or group for an issue being addressed. The organization could change the structure of the databases to link employees and groups with clients and purchase orders, but this data changes frequently and would require constant change and maintenance. For large databases with dissimilar structures and programming languages, linking becomes even more difficult.
While it would be useful to link different databases to correlate data such as purchase orders, clients, employees, and groups, reprogramming the databases and then maintaining the links between these databases could become inconvenient, inefficient, and cost prohibitive. What is needed, therefore, is a system for externally linking databases, which does not require modification of the databases. The need for such a system has heretofore remained unsatisfied.